This invention relates to magnetic bubble domain chip packages and, more particularly, to a magnetic bubble domain chip package in which in insulating film interconnect member insures exact placement of the magnetic bubble domain chip within the drive field coils and allows a reduction in the volume of the drive field coils. The interconnect member is molded in an operation which enables the molding material to be in direct contact with the magnetic bubble domain chip, thereby insuring the placement of the chip within the geometric center of the drive field coil assembly.
With the advancement of magnetic bubble domain technology, the development of a smaller, lightweight package assembly which can be mass produced in an inexpensive manner to provide a reliable magnetic bubble domain device has become a desirable goal. Because of the special requirements and operating features of magnetic bubble domain chips, the packaging of these devices presents a unique problem. Unlike the packaging of semiconductor devices, for example, the packaging of magnetic bubble domain chips requires the association of two magnetic fields with each magnetic bubble domain chip--a constant bias field perpendicular to the plane of the chip which maintains the bubble domains in a non-volatile state, and a rotary magnetic drive field in the plane of the bubble-supporting film of the chip which controls the movement of the bubble domains. The provision of the rotary magnetic drive field in a suitable packaging assembly presents an especially difficult problem. The rotary magnetic field is typically provided by winding two electrical coils in orthogonal relationship with respect to each other and then driving them with electrical signals which are 90.degree. out of phase with each other. Placing the orthogonally related coils inside a package assembly of a type heretofore known results in the signal leads to the chip being routed through the coils, thus increasing the size of the coils and, necessarily, the power required to drive them. Locating the orthogonally related coils external to the package assembly causes these coils to have an even larger volume with correspondingly larger power requirements. In addition, external placement of these coils with respect to the package assembly results in a physically awkward package of relatively large size.
Moreover, it is important to insure that the package assembly provides for the active surface of the magnetic bubble domain chip to be located at the geometric center of the drive field coils where the magnetic drive field is most uniform. When this condition is not met in a given package assembly and the magnetic bubble domain chip is offset with respect to the geometric center of the drive coils, noise interference at the surface of the chip results, thus adversely affecting its operation. Supporting structures for the drive field coils, if included in the package assembly to provide the necessary geometric relationship between the coils and the chip, tend to increase the volume of the coils with a consequent greater power demand to drive the coils.